Gas reaction aircraft power plant



Feb. 6, 1951 N. c. PRICE 2,540,991

GAS REACTION AIRCRAFT POWER PLANT Filed March e, 1942 v 8 sheets-sheet 1I /v VEN To@ /VA THA/v Y C. ,DR/CE BVM Feb. 6, 1951 N. c. PRICE2,540,991

- GAS REAcTmN AIRCRAFT POWER PLANT Filed March 6, 1942 8 Sheets-Sheet 2Feb. 6, 1951 N. c. PRICE GAS REACTION AIRCRAFT POWER P'LANT Filed Marche, 1942 8 Sheets-Sheet 3 I /v VEN Top NA 771A/v CPR/CE GAS REACTIONAIRCRAFT POWER PLANT Filed March 6, V1942 8 Sheets-Sheet 4 GII Feb. 6,1951 Filed March e, 194.2

N. c. PRICE cAs REAc'rIoN AIRCRAFT vom PLANT 8 Sheets-SheetA 5 I N VENTOR NATHAN CPR/cf Feb. 6, 1951 N. c. PRCE l2,540,991

GAs REACTION AIRCRAFT PowFR PLANT File@ Maren 6, v1942 8 sheets-sheet 7(0N TROL VAL VE LF/G -20 sa A ,R sn canmfmm (DLER FIM Y RUN/VINE 1707?#ISN ITION sumen SUR FUEL I /v VEN Ton NATHAN CPR/cf Btw Feb. 6, 1951 N.c. PllcE 2,540,991

GAS REACTION AIRCRAFT POWER PLANT Filed March 6, 1942 8 Sheets-Sheet 8 IN vf/v Ton MTHAN CPR/c5 Patented Feb. 6, 1951 2,540,991 GAS REACTIONAIBCBAIT PLANT Natllanl).V Price, Hollywood, Calif., assis-nor toLockheed Aircraft Corporation, Burbank, Calif.

Appia-suon umn s, mz, serial No. 433,599

This invention relates to prime movers :of the gas reaction'type ingeneral and more particularly to the internal combustion, reaction typesof englnes. which function in the manner commonly known as jetpropulsion. This invention finds its principal application as a powerplant or prime-mover for aircraft and the like high velocity vehiclesand particularly high altitude airplanes designed for suhstratosphere orstratosphere flight.

` In aircraft .employing the conventional propeller for propulsion.present trends in development indicate that the practical limit ofspeeds attainable therewith lie in the region of live hundred miles perhour. This limitation occurs by reason of the inherent limitations ineiilciencies of propellers as high speed propulsive units and isdetermined by their indicated abrupt falling-of! of efficiencies to .alow value which become prohibitive in power requirements at velocitiesin the region of ve hundred miles per hour. The efiiciencies ofpropellers of conventional design or of practicalsize when operatedunder rarilled atmospheric conditions are such as also substantially topreclude their use in high speed stratosphere night. Furthermore, thefrontal area of airplanes for extremely high speed operation mustnecessarily be reduced below that now le with the conventional types ofpower plants and the lifting eiclency of wings should be increased, bothof which are accomplished by the novel features incorporated in thedesign of the power plant as will be described hereinafter.

Certain features of this invention also solve the peculiarinstallational problems mociated with the type of power plant of thisinvention in the airplane, which require treatment entirely differentfrom that for conventional power plants. The method of ccs-ordinatingthe power plant design and characteristics with the airplane per se andwith accessory systems of the airplane re-` quires special and novelmeasures which are included herein within the scope of the prentinvention.

It is accordingly an objectof this invention to provide a. propulsiveunit for aircraft which does not possess the aforesaid speed limitationsof the conventionalpower plant and propeller. It is a further object ofthis invention to provide a propulsion unit which will operate ataugmented efciency at speeds and vat altitudes in excess of thosepractical with the conventional propeller apparatus. It is a furtherobject of this invention to provide a propulsive unit adapted -tooperate eiliciently at supersonic speeds and at altitudes 55 landingwheel power drive, and wing within the stratosphere. It is 8.180 anobject f 11 Claims. (Cl. 244-15) uns mvenunn u provide e propulsive unalandl associated apparatus which will be capable of imparting increased.economy and night range to the aircraft with which it is associated.

It is a further object of this invention to provide an improved aircraftpropulsive unit whichshall be economical in fuel consumption, light inweight and have a reduced frontal area in proportion to power developed.

It is a still further objective to provide a power plant incorporatingsuitable measures to insure improved operation of accessory systems ofthe airplane, .and to offer the most areodynamlcally attractive type ofpower plant installation as a whole.

It is an objective to provide a power plant which is applicable toeverytype of airplane as a basic unit, which with replacement or addition oia few minor parts,'can be made to operate superzoV sonic, near sonic, orlow speed freightairplanes.

The objects of this invention are attained in general by providing apower plant which produces propulsive work and force wholly or in partby means of the reaction of a high velocity ex- 'pansible iluld iet.

This invention resides briefly in means to efciently compress air inseveral stages by the combined eifect of impact or "ramming produced bythe high velocity of the unit relative to the air and by the action ofmultiple stage power driven compressor units of high efliclency,introduction and constant combustion of fuel ln the thus c'ompressed airto form high temperature high volume gaseous products of combustion, andutilizlng the expansion and reaction of the gases to drive thecompressors and to supply reactive propulsive force to the unit, allsubject to automatic controls acting in co-ordinatlon with certain othermechanical portions of the airplane such as power driven landing wheels,boundary layer removal fans and/or take-off propellers. l

Other objects and features of novelty will be evident hereinafter.

This invention in its preferred forms is illustrated in the drawings andhereinafter more fully described.

Figures 1 and 2 are general plan and side elevational views showing atypical installation of the invention in an airplane fuselage of anairplane equipped with foldable take-off propellers, boundary layerremoval fans.

asaopai Figure 3 is a cross-sec 3 3 of Figure 2. Figure 4 is afragmentary plan view showing a typical installation of the invention inan airplane wing.- A

Figure 5 is a cross-sectional view'taken online 5--8 of Figure 4.

Figure 6 is a cross-sectional view taken on line 6-8 of Figure 4.

Figure 7 is a fragmentary sectional view taken on line 'I-1 of Figure 4.

Figure 8 is an elevation in partial cross-section of the generalassembly of the power plant unit of the invention.

Figure 9 is an alternative arrangement of a portion of the unit ofFigure 8.

Figure 10 is a frontal view of the unit taken at onal view taken on lineline Ill-I0 of Figure 8.

Figure 11 is an enlarged detail view in partial cross-section of theaxial blower dierential accessory drive transmission for the arrangementof Figure 8.

Figure y12 is' an enlarged detail view in partial cross-section of theaxial blower diierential accessory drive transmission for the optionalarrangement of Figure 9.

Figure 13 is an enlarged fragmentary detail view of a compressorcylinder of Figure 9.

Figure 14 is an enlarged detail view of an axial blower blade showingthe method of attachment to the rotor.

Figure 15 is an enlarged detailed view of blades of the gas turbineshowing the method of attachment to the rotor.

Figure 16 is a partial cross-sectional view taken on the line I S-IB ofFigure 8 showing the arrangement of the fuel burners.

Figure 17 is an enlarged detailed longitudinal cross-section taken online I'I--li of any one of the burner tubes of Figure 16.

Figure 18 is a fragmentary cross-sectional view taken at line I8-I 8 ofFigure 17.

Figure 19 is a perspective view of a pair of the burner tubes of Figure16.

Fig-ure 20 is a typical flow diagram for the installation of the powerunit of Figure 8 in an airplane or airplane wing. Figure 21 is across-sectional view of boundary layer control apparatus optional tothat shown in Figure 20, and arranged to cooperate with the power plant.

Figure 22 is a fragmentary front elevation of a typical landing geardrive installation as may be employed in Figures 2 and 3 and arranged tocooperate with the power plant. i

Figure 23 is a fragmentary front elevation of a typical landing gear/drive installation as may be employed in Figure 4.

Figure '24 is an enlarged fragmentary crosssectional view of thevariable opening nozzle shown in Figure 8.

Figure 25 is an enlarged fragmentary crosssectional view of thecounter-rotation transmission of 'Figure 8.

4 valtitude in air of extremely low density. must necessarily handle agreat volumetric air flow. It is thereby essential that the inlet of theblower system of the power plant be made unusually large and that ithave a very high compression eiiiclency at the same time. Therefore, atthe leading end of the jet power plant as shown in Figure 8, a.cylindrical housing I0 is provided for the multi-stage axial blower C1which con- 10 stitutes the first stage air compressor. The housing I0 isprovided at the forward end with an annular opening II defined by agrooved spigot I2, both of which are of substantially full axial blowerdiameter and to winch a forwardly di- 15 rected conical ram I3comprising a tubular conduit of truncated conical shape may besemiexibly attached by means of a short exible coupling I4 as best shownin Figure 20 and also as shown in modified form at I4', I5-I6 in Figure2 2o and II--I8 in Figures 4 and 6. 'I'his ram normally extends outl ofthe leading end of the fuselage or the leading edge of thev wingaccording to the type of installation and faces forward into therelative airstream with the open end of 25 smallest diameter foremost,whereby intake air may be caught and initially compressed in the ram byimpact affected by the high velocity of the air relative to the aircraftunder flight conditions prior to its entrance into the beforesomentioned axial blower. The ram may be provided with auxiliary shutteredopenings as shown at I9 in Figures 1 and 2 to increase the effectiveinlet opening of the ram for admission of additional air when theairplane is operating at low speed as at take-off or as in a steepclimb. These auxiliary shuttered openings as shown at I9 extendlaterally, forming passageways communieating between the ram I5 and theoutside surface of the fuselage by way of the slots 620 and 40 62| intowhich the foldable propeller blades arei adapted to be housed. Asdescribed more fully hereinafter, the lateral ducts I9 are provided withspring loaded check vanes which automatically close them against outwardpassage of 45 air when the pressure inside of the ram is higher Therotor shell 20 of the axial blower C1 has a form which may be denedapproximately as a truncated, prolate spheroid, and is constructed,preferably, from a relatively thin metal tube spun to the desired shape.A plurality of axially spaced reinforcing rings 2i of suitably varyingdiameters are attached to the inside surface of the rotor shell 20 bysuitable means such as by welding and furnace brazing, one such ringpreferably being positioned opposite each row of the plurality of rowsof impeller blades 25 and adapted by suitable slotting in the rotor asshown 06 at 22 and in the said ring as best shown at 23 in Figure 14, toreceive the inwardly extending impeller blade shanks as shown at 24. Thesaid rotor shell 20 is provided with axially spaced rows of the slots 22which are shaped to fit the contour of the curved impeller blades and toposition them at their proper angles. The rings serve in operation tocarry the concentrated centrifugal forces of the blades, and to insurecircularity of the rotor while at the same time permitting the rotorshell to be made of relatively thin material.

1I carries aj. bevel gear 'I2' which!constitutes-' i portion vofv the"counterfrotation transmission .v throughfrwhich itis driven-by thegas-turbineG'. also as more fully described hereinafter; f'f Thebefore.,mentioned combustion chamber-Z into which-the final stagecompressor discharges,`

is an approximately annular-'space deflned on the Wwde'by .the housingal and on the maar by a shroudqlliboth -preferably fabricated vfromtially annular combustionlchamber Z. comprisingsaid pockets or barrels,converges at the rear end'- tojan" annular` nozzle 99 o f reduced fcrosssectional area kand containing in the portion of reduced areaapluralityY of circumilerenv tially spaced vanes as shown at 84 inFigure 8.

The said combustion chamber nozzle ring 99' serves to hold a backpressure upon the'r'comf bustion chamber and to eiliciently dischargehot gases at high' velocity 4from the combustion chamber into theexpansion zone of thei gas turbineG.;

The before mentioned 4burner tubes-99 'are each coaxially positioned andrigidly supportedwithin each of the combustion chamber pockets 81 bymeans of a streamlined tubular strut as shown atl 9| which passesradially outvthrough the combustion chamber shell 89 `and is retained ingastight connection therewith by `means of external ,nuts 99 threaded at92 -to the outwardly projecting portion 93 `of the said struts. Theinner end of the said strut makes welded connection with a perforatedcylindrical sleeve 94 in which the burner tube 98` is firmly gripped.The perforated sleeve 9| and strut 9| are preferablyconstructed of aheat resistant metal alloy such as nickel-chromium-iron. A

The burner tubes which are preferably constructed of a refractorymaterial such as Carborundum, are as previously stated, cylindrical 'ingeneral form but are constructed as best shown in Figures 17 and 19 of:two concentric tubular portions 95 and 96 which together form anintermediate annular passageway 91 having flutes make contact at theirinner vertices with the rear portion of the before mentioned inner zrearend of the said inner tube 96 is alsothus provided.

A plurality of radiallydirected holes. as shown Il, pass through theinner tubular portion of the burner at the throat portion of the Venturisection; i l

Fuel spray nozzles extend concentrically. for

a shortl'dist'ance into the forward ends of each *of the beforedescribed burner tubes as shown at I Il and each nomle carries at theinner end,

i at

' Vspaced perforations. |99 adjacent and coaxially holes'ill leadinginto the annular combustion j The said spray nozzles communicate.with'I-and are'v supported by air injection tubes hanged inletconnections |09v provided vin the portioniof the combustion chamberhousing 9|. injection tubesl make connection through suitableYmanifoldinglll to a source of compressed fair; and centrally positionedwithin 20, the air injectiontubes |91 and extending to a pointclose tothe nozzle head is a-fuel injection tube]z ||9--which makes externalconnection through a manifoldill to suitable fuel supply pumps andregulators hereinafterdescribed in The fuel spray nozzles are eachprovided with a' spider comprising a number of relatively thin radiallypositioned webs as shown at |22 adapted to nt snugly into the inside ofthe forward portion of the inner burner tube 96. The said spider thusserves as a positioning and centering support for the forward end of theinner burner `tube. Certain features of the fuel injection u means`herein described are covered in my covpending application Serial No.579,757, filed February 26, 1945, which issued as Pat. #.2'.526,4l0.V

' Making threaded connection into each of the outerend portions 93 ofthe burner tube struts 9| which extend outside of the combustion chamberhousing 85 is a glow plug 99 which serves as the igniting means for thecombustible fuel-air mixture which is formed in and ows through theburner tubes. VThe glow plug is constructed with a threaded metalbushing portion III surround- 'ing an elongated central refractoryinsulating body portion having an inwardly projecting tapered shank |99extending through the strut 9| to the throat of the burner tube, and anoutwardly extending ribbed insulating portion |93 carrying aterminal|2I. Asmall filament or coil |23 of high melting point wire such asplatinum. supported upon the inner end of the body portion of the plugis electrically connected through a central conductor bar |24, terminal|2| and a `conductor wire |32 to a suitable source of low tensionelectric current hereinafter more specically described in connectionwith Figure 20. The refractory body portion of the glow plug may becomposed of Carborundum, mica or the like insulating materials.

The described combustion chamber portion o the power plant is adapted toburn fuel efficiently over an unusually wide mixture range, in a verysmall space employing to the utmost degree the advantages of surfacecombustion. Here the fuel is uniformly dispersed prior to leaving thenozzles Vandtlfe gases of combustion formed in the burner tubes areproperly mixed with the excess.

air. The high temperatures are localized at the Y Carborundum surfaceswithin the burner tubes which are adapted to withstand heat whereas theouter casing and fuel spray nozzles, which are cxposed only vto the airstream, remain comparaconnectiorrwith the'fiow vdiagram of Figure 20.y

av Aspray head ll'ifprovided with` peripherally l with'r'espect to thebefore mentioned 18 gage chromium steel for example, to reduce weight.'I'he thin walled rotor shell reinforced by the internal rings to whichthe blades are secured form the subject matter of my co-pendingapplication Serial No. 788,350, filed November 28, 1947, which issued asPatent No. 2,501,614, March 21, 1950.

The forward end of the axial blower rotor 20 carries a coaxiallypositioned, forwardly extending hollow spindle 26 with which it isrotatably supported in suitable bearings 21 which are in turn supportedwithin the streamlined forward bearing housing 28. This forward rotorbearing housing 28 is supported and centrally positioned within theaxial blower housing inlet spigot I2 by means of a plurality ofinterconnecting, radially disposed, streamlined struts as best shown at29 in Figure 10. The struts, in addition to their structural function,serve as air straightening vanes to prevent uncontrolled swirl of air atthe inlet of the blower, thereby increasing emciency of compression. Therear end of the rotor shell 20 is closed by the inner formed half -30 ofthe housing of a fluid coupling unit F which in turn carries a coaxiallypositioned rearwardly extending spindle 32 as best shown in Figures 11and 12. The iluid coupling structure thus serves aspart of the rotorstructure, thereby conserving weight and space. Furthermore, inoperation, heat developed in the coupling is carried off by indirectheat exchange with the air being discharged from the blower. The saidspindle 32 is rotatably supported in suitable needle bearings 33 withinthe end of shaft 18 which is in turn rotatably supported centrallywithin the power plant housing by means of bearing 11 carried in asuitable lateral diaphragm or web 35.

The axial blower housing I carries on the inside a plurality of rows ofinwardly extending, radially disposed, stationary diuser vanes 31arranged to stand intermediate the rows of impellerblades 25 and fittingwith small clearances between said blades and said rotor shell. Thishousing, which may be fabricated or cast of a light weight metal such as'a magnesium alloy, is provided on the outside with a plurality ofrelatively deep intersecting, laterally and longitudinally disposed ribs36 for the purpose of imparting suflicient stiffness thereto to maintainimpeller-vane clearance to close tolerances.

The inner exhaust end of the axial blower terminates in a split, doublescroll outlet housing 38-39 having a pair of outlet spigots 40 and 4|which lead through suitable couplings 42--43 to suitable intercoolerswhich may be arranged in the airplane wings as shown at 44-45 in Figures1, 2 and 4 to 7 and also as shown diagrammatically in Figure 20, andhereinafter more particularly described.

Advantages residing in the hereinbefore described arrangement andconstruction of the axial blower are the exibility of control andrelatively high adiabatic elciencies of which the unit is capable, suchefficiencies ranging from 85 to 90 percent. This commotion also resultsin a unit which is light in weight and small in frontal area relative tothe large quantity of air it is capable of handling and supplying to thesubsequent stages of compression. The axial blower rotor`is driventhroughja planetary transmission and a fluid coupling as best shown andhereinafter described in connection with Figures 11 and 12. Located inthe intermediate portion of the 6 axial blower transmission is thesecond stage air compressor unit C2 which is preferably of a high speedmulti-stage radial flow or centrifugal blower type as shown in Figure 8.'I'his centrifugal blower comprises three additional stages ofcentrifugal compression 5|, 52 and 53 in tandem arrangement with aliquid fed intercooler 54 intermediate its first and second stages. Thistype of compressor with its integral cooler lends itself to diametrallycompact and short coupled construction and is adapted to high efilciencyoperation upon the dense air fed from the first stage compressor afterpassing through the wing surface cooler. Furthermore, the series ofradial flow impellers in tandem as shown, offers a number ofintermediate annular spaces in the main casing, which are ideal from theair flow standpoint for the incorporation, if desired, of additionalliquid fed intercoolers which may be constructed and arranged similar tothat shown at A pair of inlet nozzle connections 55 and 56 serve toreceive the first stage compressed air from the before mentioned wingintercoolers and 'to introduce it through the annular chamber 51 to theinlet 58 of the rst centrifugal impeller 59. A plurality of stationarydiffuser vanes 60 receive the compressed air from the impeller 59, andannular chamber 6| serves to direct the flow of air therefrom to theinlet of the said liquid fed intercooler 54 which is more fullydescribed hereinafter. The outlet of the intercooler 56 communicateswith the inlet 66 of the second centrifugal blower impeller 61 and theannular shaped chamber 68 formed in the body of Ithe unit in turn servesto direct compressed air leaving impeller 61 after passing through thestationary diffuser vanes 69, to theinlet 10 of the third and finalcentrifugal compressor impeller 1i. Air from the final stage impeller 1lpasses through stationary diffuser vanes 'I5 to the entrance of thecombustion chamber Z.

This beforementioned liquid cooled intercooler 54 is preferablyconstructed of a continuous metal tube wound in the form of` a compactmulti-layer helix the turns of which are coaxially positioned withrespect to the axis of the unit and with the turns spaced relative toone another by means of a plurality of perforated radially positionedfins, the whole being adapted to fit snugly in the annular chamberformed in the blower housing intermediate the rst centrifugal stagedischarge 6| and the second centrifugal stage inlet B5.

Similarly constructed intercoolers may 1- be placed in the centrifugalblower housing intermediate each of the centrifugal blower stages.

Cooling is effected by circulation of a suitable liquid coolant such asethylene glycol through the intercoolercoils and through a suitable heatexchanger external to the blower as hereinafter mentioned in vconnectionwith Figure 20 in the -,description of the operation.

The said three centrifugal blower impellers 59,- 61 and 'H are fixed toa common shaft 16 which is rotatably journaled at its forward end inbearing" as best shown in Figure ll and at the rear end in bearing 18.Bearings 11 and 18 are supported coaxially within the body of thecentrifugal "blower portion of the power unit by suitable diaphragms orwebs 35 and 80 respectively. .The forward extension of the centrifugalblower shaft 16 couples into the axial blower and accessory transmissionin a manner more fully power plant and immediately to the rear of thedescribed hereinafter. The rear end of the shaft ll v end of thecylinder |68 is provided with a bleed duct |12 connected through tubing|13 with a bleed control valve body |14 which may be located at anylconvenient place within the airplane structure. The said bleed controlvalve |14 comprises a stem |16 having a needle point |16 adapted, whenclosed, to rest upon a beveled valve seat |11. The valve bleed is ventedto atmosphere at |18. VThe said needle valve stem |16 is operativelyconnected through suitable linkage comprising lever |19, rod |88 andbell crank |8| to a fly-ball speed governorV |49 which may be drivenfrom one ofthe gas turbine accessory drive shafts such as indicated at589 whereby an increase or decrease of turbine speed will act throughthe said governor |49, to respectively increase or reduce the needlevalve opening. The lever |19 is pivotally supported at |52 upon athreaded shaft |53 by means of which the speedsetting of the governorwith respect to the needle valve action can be adjusted through a shaftextension |54 by means of a wheel |58 which may be `conveniently locatedin the flight compartment.

The movable annular throat member v|65 is so shaped that its axialdisplacement resulting from the speed responsive pressure variation incylinder |68 as influenced bythe action of the needle valve bleed |14 ascontrolled by the governo;` |49 results in an effective change of nozzlearea, at the same time maintaining streamline and high nozzleefficiency. The above described nozzle means forms the subject matter ofmy co-pending y application Serial No. 734,649, illed March 14, 1947,now abandoned.

Adjacent the trailing edge portion of the inner divergent portion of thenozzle N is an external, concentrically positioned annular jet augmentermember |82 having inner walls convergent at |88 and divergent at |84matching in contour that of the fixed divergent inner portion of thesaid nozzle N. The said augmenter member |82 is adapted to be supportedby suitable means from the body of the power unit or from the airplanefuselage or wing in which it may be installed as illustrated in Figuresl, 2, 4 and 6 and as hereinl2 another, through the action of thetransmission comprising bevel gears |85 and 82 and bevel pinions |86.

A pipe 518 for supplementary fuel, enters the combustion zone housing asshown at 584 in Figure 20 and extends radially through a tubular housing51| not occupied by an auxiliary drive shaft to a centrally positionedangle fitting 512 adjacent the forward end of the gas turbine shaft ||8.A tube 513 extends from the said angle tting 512 through a packing gland514 and into the central bore |36 of the said shaft. An oil line 515similarly makes connection at 516 with the central bore of thecentrifugal compressor shaft 16 by way of which lubricating oil may beintroduced under pressure through the rear, axial blower shaft 32 v'andinto the fluid coupling by way of opening |91 in the housing as bestshown in Figure 11.

Referring now primarily to'Figure ,l1 which shows, in enlarged detail,the type of axial blower transmission employed in the unit of Figure 8,

` the centrifugal compressor shaft 16, as before after more fullydescribed. Under certain flight conditions the augmenter increasesthrust as much as 25 percent.

Power is adapted to be transmitted from the gas turbine to the radialand axial blowers and to the various auxiliary drive shafts throughoutthe unit through 'suitable gear transmissions which comprise thefollowing apparatus:

- Referring primarily to Figures 8, 11 and 25, the forward end of thehollow gas turbine shaft ||6 carries fixed at a point just forward ofthe bearing |20, a bevel gear |85 which meshes with a plurality of bevelpinions as shown at |86, each splined to the inner end of a radiallypositionedauxiliary drive shaft as shown at |81 in Figure 25 and at |81and 589 in Figure 20. 'Ihe said auxiliary pinion drive shafts are eachrotatably supported upon a pair of suitable bearings as shown at |88 and|89 and a number of such shafts as required are arranged to passradially through the forward portion of the combustion chamber throughtubular housings v| 98 and out of the combustion chamber housing throughstuffing boxes as indicated at |9|.

Fixed to the rear end of the radial blower shaft 16 and adjacent thebearing 18 is a bevel gear 82 which also meshes with the beforementioned bevel pinions |86. Shafts 16 and ||8 are thus stated, isrotatably journaled at the fore and aft ends in bearings 11 and 18respectively. The shaft 16 makes connection just forward of the bearing11 through a conical iiange |93 with a planetary drive spider |98 whichcarries therein six parallel shafts upon which are rotatably mounted sixplanetary pinions as shown at |95.`

A further extension |96 of the shaft 16 forward of the planetary drivespider |94 enters the fluid coupling housing 38-3| and carries fixed onthe end thereof the fluid coupling impeller |99. The just mentionedforward shaft extension |96 makes a rotatable fit over the rear axialblower shaft 32 at 288. A laterallydirected drilled hole |91 is providedinterconnecting the uid coupling housing with ,the bore |98 of the rearaxial blower shaft 32 through which oil may be introduced under suitablepressure into the said cou.- pling. Annular clearance 2|| between theoutside of shaft 32 and the coupling housing entrance is provided forcontinuous escape of oil from the coupling unit.

' The before mentioned planetary pinions |95 the bevel gear 284 and theplanetary ring gear 283 are rotatably supported upon the outside shoul-`ders of the planetary spider |94 by means of apair of suitable ballbearings 285 and 286. The bevel gear 284 meshes with a plurality ofbevel pinions as shown at 281 which are carried on radially positionedoutwardly extending accessory drive shafts as shown at 288 which arerotatably supported in suitable bearings 289 carried inthe transmissionhousing 2|8. The said outwardly extending accessory drive shafts makeexternal connection with auxiliary variable speed apparatus as morefully described in connection with the auxiliary apparatus and controlsvof Figure 28. An oil scavenging line for withdrawal of oil dischargedfrom the uid coupling enters the bottom of the transmission housing atthe lowest point as shown at 585.

In Figure 9 a radial, multi-cylinder type of iinal stage compressor isillustrated which may be optionally substituted in the unit of Figure 8in place of the before described radial blower. This compressor hassimilar characteristics to the adapted to counter-rotation with respectto one u previously described tandem arranged centrifugal The gasturbine G which is contained within a cylindrical housing ||3 comprisesa tapered rotor ||8 having the approximate shape of a portion of anextremely prolate spheroid and being coaxially positioned within thepower plant with the end of minimum diameter facing rearwardly in thedirection of flow of the propellant gases. The said rotor ||5 is splinedat ||8 and bolted at |i1 to the rear end ofa hollow, tapered shaft ||8which is in turn rotatably supported concentrically within the powerunit upon a pair of shaft bearings comprising a forward bearing |20 anda rear bearing H9. The rear turbine rotor shaft bearing ||9 is supportedby means of a hollow truncated cone shaped cantilever member |24 whichis attached at its forward end of largest diameter to the transversebulkhead web 80 which separates the final stage compressor housing fromthe combustion zone and gas turbine housing.

The gas turbine rotor is provided with a plurality of rows of impellerblades or buckets as shown at |25 ln Figures 8, 15 and 26, which may beconstructed from heat resistant, high strength alloy such asnickel-chromium-iron. The said turbine rotor blades |25 are adapted tobe inserted from the inside and to make a light press fit throughsuitably shaped openings |26 broached in the rotor shell H5, and duringoperation to be held rmly in place against shoulders |21 by centrifugalforce. Internal, circular snap rings |28 adapted to lie in suitablegrooves |29 formed along the inside ends of the blade root shouldersserve to hold the blade shoulders rmly in seated position in the rotorat all times.

The plurality of gas turbine stator blades as shown at |30 and whichextend radially inward intermediate the before described rows ofimpeller blades are attached by welding at their outer root ends to theinterior surface of the cylindrically shaped turbine housing ||3.

At the apex of the turbine rotor, a conical cap member |35 encloses aspace |3| into which fuel may be injected under pressure by way of abore ,|38 within the hollow turbine shaft H8. The jsaid conical cap isprovided with a plurality of divergingly directed orifices |31equispaced invit periphery and adjacent its end of greatest diameterwhere it meets and makes oiltight connection at |38 with the rotorbodyfl |5. Injection of supplementary fuel at this point greatlyincreases the thrust of the power plantby eiiiciently dis-` tributingadded fuel to burn the excess air leaving the gas turbine Wheel andabout to enter the main propulsive nozzle. My co-pending applicationSerial No. 578,302, filed February 16, 1945, which issued as Patent No.2,479,777, Aug. 23, 1949, is directed in part to the injection of fuelfrom the apex portion of the turbine rotor.

The thrust output of the power plant is enhanced by operation withrelatively high temperature gases entering the gas turbine. Thelimitation of temperature has a structural basis. The gas turbine canoperate in a higher tempera ture range than that of conventionalturbines because of the structural provisions and cooling arrangementsprovided.

` A truncated cone shaped baille |43 is provided as a rearward extensionof the inner shroud 88 of the before mentioned combustion chamber Z. Thetapering annular-like space |44 thus formed between the conical shapedouter turbine bearing support |24 and the said inner combustion chambershroud 88 and the baille |43 serves to conduct cooling air undersuitable pressure from the annuiar forward end of the combustion chamberat |48 to the inner apex of the turbine rotor adjacent the bearing ||3and thence counter-current to the propellant gases in the turbine asshown by arrow |48 back along the inner surface of the turbine rotor 8and in contact with the inner ends of the rotor blade roots |21 to theopenings in an annular cooling air nozzle ring |41 which is immediatelyinside of and concentric with the gas turbine nozzle ring 90. Aplurality of drilled ducts'as shown at |42 are provided for conducting aportion of the cooling air from the inside oi the rotor to the annularcooling cavity |33 formed between the taper |40 adjacent the end of theturbine rotor shaft and an adjacent relieved concavity |4| in theturbine rotor. A plurality of exhaust nozzles |48 are provided forexhausting cooling air from the cavity |38 into the secondary combustionchamber S and are in the form of drilled cap screws which pass throughsuitable holes in the cap |35 and make threaded connection into nipples|50 which are welded at |5| to the turbine rotor body. The said nozzlesthus also serve to retain the Acap |35 in oiltight position on the apexend of the turbine. The turbine cooling system forms the subject of mycopending application. Serial No. 573,562, filed January 19, 1945.

Immediately to the rear of the gas turbine and attached at |55 to thegas turbine housing, is the secondary combustion chamber S and nozzlesection N which comprises an approximately Venturi shaped housing |58carrying a refractory lining |81 which may be Carborundum or the likematerial, as best shown in Figure 24. The secondary j combustion chamberis shaped to utilize the Vkinetic energy of the residual gas velocityfrom the turbine wheel so that it is additive to the kinetic energy ofthe propulsive jet.

An annular baille |60 having a streamlined section similar to that of anairfoil is concentrically supported adjacent the gas turbine exhaustwithin the entrance to the secondary combustion chambers anddiametrically opposite the secondary fuel orifices |31 in the rotor .cap|35 by means of a plurality of radially directed interconnectingstreamlined struts |8|. This baille is preferably constructed with aleading edge portion |82 of heat resistant metal such as anickel-chromiumiron alloy and a body and trailing edge portion |83 ofCarborundum or the like refractory material.

The nozzle portion N is provided with an inner longitudinally movableannular throat member |85 supported upon a plurality of parallel,axially positioned rods |88 which extend through and make a sliding fitin suitable holes in the nozzle lining and are fixed at the inner endsto an annular shaped servo piston |61 located within an annular shapedservo cylinder |68 in the nozzle body as best shown in Figure 24. Thepiston |81 and annular throat member |85 are urged rearwardly by meansof a number of coil springs |83 acting under compression against theforward or rod side of the said annular piston.

The said parallel axially positioned rods |88 upon which the annularthroat member |85 is movably supported, are provided with coaxial boresas shown at |10 which extend through the servo piston |51 and thusprovide pressure equal- `izing passages through which gases from the l|98 of the hollow axial 'blower shaft 32 and thence through the lateralpassagei 91 into the fluid coupling housing 30--3I.

The balance of the axial blower transmission is identical with thatemployed in connection in connection with Figure l1.

Referring now principally to Figures 1 to 3 in which a typicalinstallation is shown,

RC1C2ZGSN with the radial blower and hereinbefore described dynamicbalance. The leading end spigot I2 of the axial blower Cr makessemi-flexible connection at |4 as by a short reinforced neoprene hosefor example, to a tubular extension conduit I6 which in turn makessemi-flexible connection at I4 to the rear end of the conical ram I5.The i forward end opening of the ram I5 extends through the foremost endof the fuselage as shown at300. Y

The nozzle S of the unit is positioned to discharge rearwardly through aVenturi shaped jet augmenter member |82 having a forwardly convergentportion |83 and a rearwardly divergent portion I 84 faired into andforming the lower rearward portion of the fuselage. An air duct ofsemi-annular 'extent and opening inwardly through the fuselage skinforms the forward lower exposed edge of the forward portion |83 of theaugmenter member |82. The balance of the forward portion of theaugmenter member |82 also communicates throughan annular duct 302 withthe confined space around the power unit defined by a shroud 303 whichin turn makes lateral connections with the inner lateral passages 304within the wings which lead through the plurality of fans as shown at305-308 from the boundary llayer removal slots 308-3I2 which openthrough the top skin of the wing.

The axial blower outlet spigots 40 and 4| each make connection throughsuitable conduits as shown at 42 and 43 to wing skin intercoolers 44serve to transmit rotative power from the power and 45 whicharepositioned spanwise in the wings. Each skin intercooler comprises anairtight outow anda return flow portion 46 'and 4l interconnected at 3|4and preferablyfounded i in part by a portion ofthe upper and lower wingskins respectively and adapted thereby to permit heat exchange directlythrough those portions of the wing skin to the relative air streamnowingin contact with the outside surface thereof. The pressure of the airdischarged from the axial blower is suiciently low to permit it to beconfined in this manner directly in suitable portions of the wingstructure, as for example, in corrugations directly underlying the skin.Thus the air can be intercolled to a temperature close to that of thewing-air boundary layer. The said return portions 41 of the wingintercoolers make connection through ducts 3|5 and 3|5' with the inletspigots '55 and 56 of the second stage compressor Cz.

As shown in Figures 1 to 3, at the forward end of the fuselage andsurrounding the ram I5 'a 16 pair .of propellers 3I8 and 3If| arerotatably mounted upon hollow lhubs 3|8 and 3|9 and adapted tocounter-rotation through suitable gearing by means of a pair of parallelshafts 320 and 32| which extend forward along the sides of the powerunit. These parallel shafts are driven `through bevel gears as shown at322 and 323 in Figures 1 and 3, from laterally extending auxiliaryshafts such as those shown at 208 and 388, which enter the axial blowertransmission as hereinbefore described in connection with Figures 11 and12. The forward ends of the shafts 320 and 32| terminate in straddletypes of pinions as shown at 628, 626 and 621 supported by bearingsshown at 628 and 629. The centrally forward propeller hub 3|8 in adirection counter to that of hub 3|9. The foremost hub 3|8 and dividedgear 63| are rotatably carried upon suitable ball bearings 632 and 633and the rearmost propeller hub is rotatably carried on a pair ofsuitable ball bearings as shown at 634 and 635. Recesses 620 and 62| areprovided in the nose of the fuselage to receive the propeller bladeswhen they are folded and inoperative. These propeller shafts, and alsothe shafts used for driving landing wheels or boundary layer removalfans, are adapted to operate at high speeds, and thus may be very smallin diameter and light in weight.

'For example, these shafts may be approximately 3A." in diameter andoperated at speeds of approximately 40,000 R. P. M. It has been foundthat such shafts can be used without diiiiculty The series of boundarylayer removal fans 305-308 contained in suitable housings provided ineach wing are rotatably carried on laterally extendinglay shafts 325 and326 which are driven from obliquely extending auxiliary drive shafts 321and 328 through suitable bevel gears 324 and -32|), as shown in Figure3.

A lateral auxiliary drive shaft 330 extending vertically from thelower'side of the unit is coupled through bevel gears 33| and 332 to alpair of oppositely. extending shafts 333-334 which, acting throughbevel gears at 335 and 336 and suitablev clutching mechanism hereinaftermore fully describedin connection with Figure 22,

unit transmission to the main landing gear-,wheels 331 for assisting` intake-olf and ground maneuvers.

In Figure 22 an enlarged detail view of the power driven, retractablelanding gear of Figures 1 to 3 is shown.. The shock absorbing strutcylinder 338 is pivotally connected at the top to internal structure 333of the wing by means of a pair of trunnions 340 and 34|. The landinggear wheel 331 is rotatably mounted upon an axle 342 which is supportedhorizontally beneath the shock absorbing strut byvmeans of a yoke 343. Awheeldrive ring 344 provided with internal lteeth, forms an integralpart of the wheel hub 345 and is adapted to mesh with a drive pinion346. The said drive pinion 346 is fixed upon the outer end of ahorizontal pinion stub shaft 341 which is rotatably journaled in a pairof bearings 348 and 348 on either side of the gear box opening 380formed in the enlarged portionV 35| of the 4yoke 343. Splined to thecentral portion of the pinion shaft 341 and within the gear box.

it is adapted for ahigh compression ratio in a small space and at high'lciency of air which is already comparatively dense. In installationswhere liquid type intercooling is more diilicult to carry out, themulti-cylinder compressor will be preferred. However, in general, thecentrifugal compressor with integral liquid fed intercoolers will oilerthe advantage of simplicity and use of only rotating parts.

The multi-cylinder compressor is provided with a double row arrangementof a plurality oi' radially disposed cylinders as shown at R1 and Rz ofFigure 9, one of such cylinders being shown in the enlarged longitudinalcross-sectional view o! Figure 13 and two opposite cylinders, 2|2 and2|3 of the two adjacent rows R1 and Rz being shown in cross-section inthe longitudinal cross-sectional view of Figure 9. The pistons, as shownat 2|4 and 2|5 are carried on the outer ends of hollow piston rods, asbest shown at 2|6 in Fig- `ure 13, which pass through suitable stuiilngboxes as shown at 2|1 in the inner heads.2|9 of the cylinders. 'I'he'said pistons are thus adapted to be double acting, each performing twocompression strokes per piston cycle and operate at about 5,000 R. P. M.in a representative case.

The inner ends of the piston rods terminate in cross-heads, as shown at220, which are adapted to reciprocate within suitable radiallypositioned cross-head guides 22| carried within the body of thecompressor crankcase. The connecting rods 222 make pivotal connectionwith the cross-head Wrist pins at their outer ends, and with pinbearings at their inner ends in a suitable iloating link collar 225. Dueto the symmetrical arrangement of the cylinders and the use of doubleacting cylinders, racking forces on the collar 225 are small,particularly at high speed, hence the collar may be permitted to floaton the crank pin.

In some cases a, positive mechanism, not shown, may be provided toinsure uniform motion of the collar, as for example abutments on thelink rods, which contact the collar at a period of maximum rodangularity. The crankshaft 230 is provided with suitablecounter-balances as shown at 23| and is carried on two crankshaft mainroller bearings 233 and 234 which are supported within the crankcase onsuitable webs as shown at 235 and 236 in Figure 9. Fixed to thecrankshaft intermediate its main bearings 233 and 234 is a crankshaftdrive gear 231 which is driven by means of four lay shaft pinions, oneofwhich is shown at 238.

The cylinder heads for both ends of the compressor cylinders areprovided withvpassage ways or ducts as shown at 24U-24| in Figures 9 and13, leading from the discharge valve ports as best shown at 242 to 245in Figure 13, to the compressed air outlet manifolding as shown at 246and 241 in Figure 9. The discharge ports may be provided with anysuitable type of valve such as the well-known automatic spring feathervalves 'commonly used in air compressors.

The inlet valves to the compressor cylinder are preferably of the sleevetype as shown in Figure 13 to insure large induction area withoutincreasing clearance volume. The sleeves 250 which are adapted to moveover the inlet ports 25| and 252 provided around the periphery of thecylinders adjacent the cylinder heads, extends the full length of thecylinders and is adapted to be actuated and reciprocated by a valve gearof the Argyle type as shown at 253. One Argyle valve dlacent rows serveto actuate the two valve sleeves. The Argyle valve gears of all of thecylinders are driven by means of a common ring gear 254 of a largediameter surrounding the .crank case between the cylinder rows, and thesaid ring gear is in turn driven from a pair of the before mentionedcentral lay shaft pinions,v

one of which is shown at 238, and through a pair of gears 248 and 249 ofsuitable gear ratio and rotatably mounted upon a common spindle 225Journaled upon a pair of suitable bearings as shown at 221 and 228.

The inlet ports 25| and 252 of the compressor cylinders open 4directlyinto the enclosed space 251 formed around the cylinders by the shroud258. Inletspigots 255 and v256 are provided entering the shroud 255 forfeeding ilrst stage compressed air from the external intercoolers to theshroudenclosure and thence to the inlet ports of the cylinders for theilnal stage of compression. Such a compressor may provide a ratio ofcompression of 9 to l, for example.

When the piston type of i'lnal compression, as Just hereinbeforedescribed is employed, the forward end of the gas turbine shaft ||8counterdrives a stub shaft 260 which carries a driving gear 26| which inturn meshes with four rear lay shaft drive pinions, one of which isshown at 262 in Figure 9. Each of the lay shaft drive pinions is in turncarried on four lay shafts one of which is shown at 253. The lay shaftspass through the compressor crankcase and are each rotatably supportedupon four sets of bearings as best shown at 261, 268, 269 and 210 inFigure 9. The central lay shaft pinions mesh with the compressorcrankshaft drive gear hereinbefore mentioned.

The forward four lay shaft pinions, one oi which is shown at 21 meshwith the axial blower transmission drive gear 215 which is xed t0 theplanetary drive spider 218 and rotatably supported at |30 upon the axialcompressor spindle 32 by means of a hollow concentrically positionedshaft 216. The said hollow shaft 216 passes forward through an opening211 in the rear housing 3| of the fluid coupling unit F and carriestherein the fluid coupling impeller |99 before mentioned and shown inconnection with the mechanism of Figure l1.

The planetary drive spider 218 carries a plurality of parallel. axiallypositioned shafts upon which the planetary gear pinions are rotatablymounted. The said planetary pinions |95 mesh with the planetary ringgear 203 on the outside and a sun-gear 20| on the inside. The planetaryring gear 203 is rotatably mounted upon the outside shoulders of theplanetary spider 218 by means of a pair of ball bearings 205 and 206 andthe sun-gear 20| is splined at 202 to the before mentioned axial blowerspindle 32. The ring gear 203 carries fixed thereto a bevel gear 204which meshes with the plurality of bevel pinions 201 which are rotatablysupported upon radially directed shafts as shown at 208,

in suitable bearings as shown at 209. 'Ihe shafts extending radiallyfrom these bevel pinions serve to drive various accessories ashereinbefore described in connection with Figure ll.

With this arrangement of the transmission, lubricating oil is introducedunder pressure into the iluid coupling through a pipe 500 which entersthe housing at 58|, and thence through an angle tting 582 and through atube 583 extending through a packing gland 584 into the bore gearpositioned between eachpairot cyliruiersin` 'shafts 263 and 363andobiiquely extending auxiliary shaft 611 andIIl-fronrtlre axial blowertransmission. These auxiliary shafts make driving connectionthroughsuitable gearing u8 shown at 383, I and lll ill-Figures! and 5andoneofwhichisasillustratedat369in Figure 20, with the plurality of thebefore mentioned longitudinally positioned drive shafts 332 to 364 ofthe boundary layer removal fans 335 to 351. The auxiliary shaft 233makes driving connection with one or'more centrifugal coolantcirculating pumps as shown at 426. The suction of said coolant pump 429connects through suitable piping 42| with the outlet connection of acooler 422 not shown in the gures but which may be located in anysuitable pomtion within the fuselage or wing and preferably adapted toeffect heat exchange from the coolant to the air stream through thefuselage or wing skin. The discharge` from'the coolant circulation pumpconnects through pipe 423 with the inlet of the surface intercooler 54in the centrifugal blower housing. 'I'he coolant outlet 424 of the saidsurface intercooler is connectedto the inlet of the cooler 422 throughpipe 425. Ethylene glycolor the like fluid may be employed as thecirculated coolant material.

the chamber 43|. Thetopoftherod 4461s rotatably connected throughsuitable gearingg,

l to a mamial'adjustlng meanalwhich The pressureof the air in the secondstage l compression portion of the power plant is so highthatitcannotbereadilytransmitteddirectlyto the airplane structurewithout weight penalty. Furthermore, the loss of high pressure air wouldbe considerable through any small leaks which might occur. For these andalso to avoid air ducting pressure losses, the liquid type intercoolerls advantageous for the high pressure'air region of the power plant. Insome installations for military Ythe liquid type intercoolermaybeusedalsoatthedlschargeoftheaxial blower, From a tactical standpointthe liquid intercooler is particularly desirable because if it ispunctured by gun fire only the intercooling is rendered ineffective. andno air is lost. Hence the power plant can continue to function at-`closed in United States letters Patent No.v

2,294,350. Accordingly. said fan blade pitch varying mechanism in eachhub is adapted to be actuated by means of push-pull rods which enter thefront point of the hub 426 coaxially as best shown at `429 in Figure 20.Inward and outward motion of the rod 423 moves the fan blades topomtions ofsmaller or greater angles of incidence relative to the airupon which said blades act when in rotation. A bell crank 436 pivotallysupported within the airplane wing at 43| serves to reciprocably linksaid push-pull control rod 429 with rod 432 which is in turn'pivotallyconnected at 433 with the outer end of a lever 434. The central pivot435 of the said lever 434 is pivotally carried at the lower end of a rod436 which extends out through a stulng box in the wall of a closedchamber 433. The said rod 436 makes connection at its inner end with thefree end of a closed Sylphon bellows 433. The opposite,

v or relatively fixed end of the said Sylphon bellows 439 is carried onthe lower end of a threaded adjustable rod 44| which extends upward andout through a stumng box inthe upper wall of locatedintheiiightcoinpartment of the airplane.

The end of lever 434 opposite to pivot connection 433 makes rotatableconnection by means of a suitable ball and socket joint 445 to the outerend of a needle valve Istem 446 of a needle valve 441 adapted to beclosed upon extended downward movement of said stem. Pipes 446 and 449make connection with the inlet and outlet connections respectively ofsaid valve.

A spring 456 normally acting under compression, extends between theupper end of the needle valve stem joint 445 and a nxed portion 45| ofthe bellows chamber 436.

The interior of the bellows chamber 436 is connected by tubing 452 toone or both of the axial blower outlet scrolls as shown at 453 wherebythe Sylphon bellows 439 is subjected on the exterior thereof to airpressure corresponding to that of the said axial blower discharge.

The central pivotal portion 435 of the lever 434 is elastically coupledby means of a coil spring 455 to one/end of a horizontal lever 456 whichmakes pivotal connection at the opposite end 45I- with the outer end ofa primary fuel valve piston rod 466. A coil spring 46| serves as anelastic linkage between an intermediate point 462 of the lever 456 and acontrol lever 463 which may-be located in the flight compartment in suchposition as to be conveniently manually operated by the pilot or flightengineer in a manner similar to the conventional engine throttle. Incase the pilot or flight engineer's control station is remote from thepower plant control accessories. the throttle control lever 463 may beactuated from such remote station through suitable linkages or cablecontrols, not shown.

The above mentioned throttle control lever 463 is plvotally supported at465 upon a suitable mem--- ber of the airplane structure.

At a point 466 on the control lever 463 intermediate the attachmentpoint of the before mentionedl spring 46| and the lever pivot 465, asecond coil spring 461 normally acting under compression makes anelastic linkage to the outer end of a secondary fuel valve piston rod466. An extended portion 469 of the control lever 463 is adapted uponrotative movement of the control lever 463 along the sector 416 in thedirection of the arrow 41| to ilrst actuate the ignition and fuel pumpswitch 412 and then the starter switch 413 in succession.

The before mentioned primaryand secondary fuel valve piston rods 466 and466 enter through stuffing boxes 415 and 416 into the fuel valve housing411, and are reciprocably supported and guided therein by anintermediate divisional wall 419 through which they slidably pass in aliquid and gas-tight t. The inner ends of the piston rods 466 and 466terminate in needle points 43| and 462 which are adapted, in the closedpositions, to seat upon corresponding beveled outlet valve seats 463 and464 from which outilowlng fuel pipes 465 and 466 extend.

The said piston rods 466 and 466 carry a pair of pistons 461 and 466flxed thereto at an intermediate point which make fluidtight sliding fltin a pair of cylinder bores 469 and 490 formed within the lower half ofthe valve housing 411 and interconnected at both ends by ducts 49| andof said cylinder bores by means of which a di!- 17 369 is a helical gear352. The helical gear 352 meshes with a helical pinion 353 carried upona drive shaft 354 which extends parallel with the axis of the landinggear strut through a housing 355 on the outer face of the yoke and intothe gear box 350. The lower end of the said shaft 354 is supported in abearing`356 at the bottom of the gear box.

The upper portion of the shaft 354 makes a longitudinally slidablesplined connection with the tubular shaft 351 which is rotatablysupported from the cylinder 338 by means of a -pair of bracketedbearings 358 and 359. Rotation is imparted from the before mentionedaccessory shaft 3,33 to the landing gear strut shaft 351 through a coneclutch 368 and a movable clutching member 366 splined to a stub shaft360 and bevel gears 335 and 336. The movable clutching member 366carries a double acting piston 362 adapted to be reciprocated in acylinder 363. Upon vapplying differential fluid pressure upon the piston362 through pipes 364 and 365 the cone 366 may be moved into frictionalengagement with either the stationary braking surface 361 or the drivingsurface of the clutch 368 carried on the end of the before mentionedaccessory shaft 333. It will be apparent that to the describedmechanical friction components there exist hydraulic or electromagneticequivalents, such asv hydraulic couplings which may be employed inessentially the same manner, thereby falling within the scope of theinventive idea.

In Figure 23 an optional form of landing gear arrangement is shown moreparticularly suited to installation in a multi-motored aircraft of thetype illustrated in Figures 4 to 7. Here the fluid actuated clutchingand braking mechanism may be identical to that shown and described inconnection with Figure 22 and may be driven through suitable gearsassociated with the auxiliary shafts 6|1, 6|8 and 6|9, 620 extendinginto the wings from the axial blower transmission of the unit as bestshown in Figure 7. The driving power is thus transmitted through thelaterally extending auxiliary shaft to a helical pinion 600 through avertical shaft 60| having a pair of universal joints 602 and 603 toallow the gear to be retracted within the wing or suitable nacelle. Thesaid helical pinion 600 meshes with a helical gear 604 which is xed tothe intermediate portion of a horizontal stub drive shaft 605. A pair ofpinions 603 and 601 fixed on the ends of said shaft 605 serve to drivethe ring gears 608 and 609 forming parts of the hubs 6 I0 and 6|| of thetwin wheels SI2 and 6|3. The axles for the twin wheels form a continuoustruck member 6|4 which is laterallyl pivotally connected at 6 I 5 to thelowerV end of the shock absorbing strut 6 6 in such manner as to therebyequalize the loading on the wheels by allowing the wheels to followirregularities in ground surface.

Referring now principally to Figures 4, and 6, an illustration of atypical installation of the power unit within an airplane wing is shown.The leading and trailing edges of the Wing are shown at 369 and 310respectively, and the upper and lower cambered skin surfaces thereof at31| and 312. The power unit RCiCzZGSN is shown submerged within the wingwith its axis approximately on the chord line and perpendicular to thespan of the wing. The forward end portion of the ram R emerges from theleading edge of the wing at 313 and 314 and the trailing portion of thenozzle augmenter |82 emerges from the upper A 18 and lower trailing edgeportion 'of the wing skin at 315 and 316.

In the upper skin of the wing, boundary layer control slots may beprovided as shown at 311 and 319 and both upper and lower surfaces withaugmenter air duet slots as shown at 390 and 38| and more fullydescribed hereinafter.

The outlet spigots 40 and 4I of the axial blower C1 make connectionthrough suitable curved ducts 42 and 43 to the outward ow passages46--46 of the spanwise arranged wing skin intercoolers 44 and 45. Thereturn passes 41-41 of the wing skin intercoolers 44-45- make connectionthrough suitable curved ducts 3| 5--315 to the inlet spigots 55 and 56of the radial blower compressor Cz.

The two auxiliary shafts 208 and 388 laterally projecting from the axialblower transmission as shown in Figures 4 and 7, 'extend spanwisethrough the wing and make geared connections at 389, 390 and 39| with aplurality of longitudinally positioned shafts as shown at 392, 393 and394 which are adapted to drive boundary layer removal fans 395, 396 and391.

Each of the boundary layer removal fans 395-391 communicates on thesuction side with the before mentioned boundary layer removal slots 311and 319 through suitable passages within the Wing defined by the upperand lower wing skins and intermediately positioned walls las shown at399 and 400. The exhaust ends of the fans communicate through similarlyformed conduits as shown at 40| and 402 with a spanwise extendingpassageway 403. The 'said spanwise passage within the Wing into whichthe boundary layer fans exhaust communicates with the augmenter at thenozzle N through a substantially annular passage formed between the gasturbine and secondary combustion chamber housings G and S and thesurrounding c onically shaped baille walls, the upper and lower sectionsof which are shown at405 and 406 in Figure 6 and the side wall sectionsof which are shown at 401 and 408 in Figure 4.

The lateral air passage 403 may also communicate with a plurality ofboundary layer control discharge slots opening through the upper skin ofthe wing as shown at 4|0-4I2. Walls 414 and 4|5 make an airtight sealaround the forward part of the axial blower portion of the power unitwhereby substantially the entire length of the unit can be contacted andcooled by air circulated by the boundary layer fans. Compared to suctionslots, discharge slots increase the kinetic energy of the boundary layerratherthan swallowing the stalled boundary layer. Both types of slotsreduce the momentum of vwing wake, thereby improving aerodynamicefficiency of the airplane. The boundary layer removal and control meansand system form the subject of my copending application, Serial No.572,924, filed January 15, 1945, which issued as Patent No. 2,514,513July 11, 1950.

Referring now to Figure 20, a flow diagram illustrating the arrangementof suitable piping, manual and automatic controls, and auxiliaryapparatus which may be associated with the power unit for itsinstallation in an airplane, is shown. For convenience, the installationof the power unit of the preferred type illustrated in Figure 8 will befirst considered in relation to the typical installation thereof in anairplane in the manner of Figures 4 to 7.

The power unit hereinbefore described and as shown at RCiCaZGSN isprovided with a pair of yor through pipe 55| intercooler 552 and returnpipe 553 to the said nozzle 542. The"` exhaust 555 from nozzle 542 maybe connected through the pipe 556 to the cabin enclosure of theairplane, a fragment `of the skin of which is illustrated at 561 inFigure 20. The before mentionedltwo-way cock 549 is adapted to beoperated to direct flow of air from pipe 544 either through pipe 550 or55| or to divide ilow between them in accordance with the temperature ofoutflowing air at 558. The said control ofcockV 549 is accomplished bymeans of a temperature sensitive device such as a thermostat at 559acting through a suitable coupling 566 iand actuating device 56|. TheIntercooler 552 is preferably of the skin surface type and may belocated in any suitable place within the fuselage or wing structurewhere heat exchange with the air stream can be effected. I'he cabinair-conditioning system forms the subject of my copencling application,Serial No. 575,913, filed February 2, 1945,*which issued as Patent No.2,438,- 046.

The generator E is adapted to supply a charging current throughconductors 565 and 566 to a suitable bank of storage batteries 561. Adifferential voltage sensitive `switch 568 serves through suitablecoupling 569 and valve actuating means such as a solenoid 546' toactuate the nozzle control valve 546 in such a manner as to increase ordecrease air supplied to the` turbine in accordance with batterycharging and electric accessory current needs. The differential voltagesensitive switch 568 is of a conventional voltage operated type and isso constructed and ar- `ranged as to energizev an electromagneticallyacv tuated means 546 to open the throttle valve 546 when the voltage ofthe battery 561 drops below a predetermined value and to close thethrottle valve 546 when the voltage of said battery rises above apredetermined value.

The operation of the apparatus of this invention primarily that shown inthe installation of Figures 5, 6 and 1, following, for convenience, thesequency of operations from starting ofthe power unit to cruisingconditions, is as follows:

The control lever 463 is first moved along the sector 410 from the stop"position to thev position indicated as ignition In so doing, the leverextension 469 actuates the ignition snap switch 412 to complete the lowvoltage electric circuit through the glow plugs by way of conductor |32and return through the ground connection. The use of a low voltageignition circuit of this type has the advantages of simplicity, freedomfrom creating radio interference, and eiliciency, especially at highaltitudes where corona losses and insulating diiliculties are prevalentwith the conventional high tension systems commonly employed forinternal combustion engines. At the same time the fuel pump .motorcircuit is also closed by the same switch to complete the batterycircuit from battery I I through the rheostat 506 and the conductor 5|3.At this position the rheostat contact arm 561 is at a position on theresistance windings 566 of maximum resistance and corresponding minimumpower input to the fuel pump, At this position pressure. When thefilaments of the glow plugs have reached the ignition temperature of thegas fuel mixture to be subsequently introduced and the fuel pressure hascome up to the starting pressure, the control lever 455 is'then advancedto the "starter" position which acuates the starter switch 415 tocomplete the electrical circuit from the battery vliflii through theconductor 5|4the solenoid 545' of the starter air valve 545andreturnthrough the ground connections. This completion of the startercircuit results in :opening the valve 545 and admitting air from thepressure flask 525 through lines 544, 545, and regulating valve 545. tothe nozzle 54| of the air starter turbine wheel 551. This turbine wheel,which is designed particularly for starting with a` relatively smallflow of air may be relatively small in size for example it may be sixinches in diameter and capable of delivering about 30 BHP.

The resultant torque from the turbine wheel 551 f is transmitted throughthe overrunning clutch 545 and shaft |61 to the intermediate pinion |55as shown in Figure 25, which meshes with gears |65 and 82 and drives thegas turbine shaft |l5 and the blower shaft 15 in counter-rotation withrespect to one another. As soon as the turbine andthe blowers are uptoabout 15 percent of normal speed sumcient air will be self-supplied bythe blower and the compressor o i the unit to the combustion chamber toestablish an appreciable differential-pressure in the Pipes 495 and' 494which lead respectively to the point of discharge of the second stagecompressor into the combustion chamber at 495 and to the Venturi sectionof one of the burner tubes as best shown at 491 in Figures 17 and 18;This said differentialv pressure is communicated to the fuel valveactuating pistons 451 and 455 in the interconnected. cylinders 469 and496 and is such'as to tend to move the fuel control needle valvesdownwardly olf their valve seats 455 and 454.

At the starter position of the control lever 465 on the sector 416, thespring 461 'is under suilicient compression to hold the needle valve 454firmly closed, but the compression. in spring 46| is at this point sobalanced that as soon as the now of air through the burner tubes isestablished to a given value duringthe starter cycle, the abovementioned resultant differential pressure acting upon the piston 451 issufiicient to crack" the needle valve 463 and allow a roper amount offuel to flow through line 465 the primary fuel Jet manifold i2 andthence to the spray jets |66 in the burner tubesV to initiate operationof the power unit. The unit is thus started and brought up to idlingspeed.

The unit thus becomes self-motoring at approximately 15 per cent ofrated speed and a smaller amount of starting air is required `than ifair were released from the tank directly to the inlet of the gasturbine, the flow passages of which are obviously disproportionatelylarge for starting purposes. At idling speed the overrunning steps to 4of the sector 415 in the direction indicated by arrow 41|, thecompressive force of the spring 46| is further relaxed, tending to allowthe primary fuel needle valve to open further and to feed a greaterquantity of fuel to the 2l ferential pressure can be established on thepistons 481 and 408 are shown at 499 andv 494 respectively. -The saidpressure pipe connection 493 leads to the final stageair compressordischarge at the inlet |45 to the combustion chamber through 'an inletnipple 495 through the combustion chamber housing and the vacuum pipeconnection 494 makes connectionI through the combustion chamber housingat 495 to the Venturi section ofy one of the burner tubes as 'shown at491 in Figures 17 and 18.

Carried on the before mentioned piston rods 460 and 468 adjacent theneedle points 48| and 482 are another pair of pistons 498 and 499respectively which make a loose sliding iit in cylinder bores 500 and50| formed in the upper half of the valve housing 411 above the divisionwall 419 The lower head ends of the said cylinder bores 500 and 50| areinterconnected by a duct as shown at 502 and are connected externallythrough a fuel supply pipe line 509 which leads from a pressure fuelfeed pump P which in turn takes suction directly from the bottom of afuel storage tank T to avoid possibility of suction line vapor lock. Theupper head ends of the cylinder bores 500 and 50| are provided withcentrally located outlet ports 489l and 484 which constitute the beforementioned beveled `needle valve seats upon which the needle points 40|and 402 of the upper ends of the piston rods rest when in the closedposition. The said outlet ports 403 make connection through the fuelsupply pipe line 485 to the primary fuel burner nozzle manifold |2 andthe outlet port 404 makes connection through the fuel supply line 486 tothe combustion chamber housing at 504 and thence through the bore |96coaxially positioned within the gas turbine shaft ||9, to thesupplementary fuel burner oriiices |91.

A rheostat 506 having a common support with the fuel valve housing isadapted to be operated to vary the resistance thereof by means of amovable contact arm 501 pivoted at 500 and adapted to be actuatedthrough a link 509 interconnecting the lower end of valve rod 460 andcrank 5|0. The electrical circuit thus adapted to be varied is completedby means of the before mentioned suitable one of the auxiliary shaftsextending from the counter-rotation transmission, is a centrifugal airbooster pump 590 which takes suction through line 59| from the dischargeof the ilnal stage air compressor at its inlet to the combustionchamber. 'Ihe pump 590 discharges through pipe 592 to the injection airmanifold I I leading to the fuel spray nozzles in the burner tubes asbest shown in Figure 17. 'I'his insures improved atomization of the fueland removes radiant heat from burner nozzle parts by conignition andfuel pump snap switch 412 through battery 5|I, conductor 5|2 and saidresistance 506, through conductor 5|3 to 'the fuel pump motor M1 andreturn by way of the ground connections shown. The electrical powerinput to the fuel pump drive is thus adapted to be varied as a functionof the-throttle setting and the fuel demand. At the same time a parallelcircuit through the ignition glow plugs is completed lby said switch 412from battery 5|| through conductor |32 and return through the groundconnections. The fuel metering and powerplant control system hereindescribed forms the subject matter of my co-pending application SerialNo. 744,238,

filed April 26, 1947, and the system for starting the powerplant formsthe subject matter of my co-pending application Serial No. 615,167, ledSeptember 8, 1945, now abandoned.

The before mentioned oil line 449 connects through pipe 506 to theoutlet of a centrifugal oil pump 581 which takes suction through pipe580 from the oil scavenging outlet connection 505 in the bottom of theaxial blower transmission housing. The oil pump 501 is adapted to bedriven by an auxiliary drive shaft 509 which extends laterally from thecounter-rotation transmission of Figure 25.

Also driven b y auxiliary shaft 509 or another 15 vection.

Referring now to Figure 2l, an optional form of boundary layer removalmechanism is diagrammatically illustrated which may, under certaincircumstances, be desirable over that shown in Figure 20. Here theauxiliary shafts 209-980 extending from the transmission makes direct'driving connection through suitable gearing with rotors such as shown at5|5, of a centrifugal blower 5|6 suitably housedwithin the wingstructure. A duct 5|1 connects a boundary layer removal slot 5|8 in theupper wing skin with the suction inlet 5I9 of the blower. An outlet duct520 connects the discharge of the blower withy A cylindrical a boundarylayer control slot 52|. valve 522 eccentrically rotatable about center523 serves to reducevthe area of the opening of slot 52| and lto closeit upon counterclockwise rotation to its extreme position and to openand increase the slot area upon clockwise rotation thereof. Rotation ofsaid cylindrical valve 522 is effected by a lever 524 associatedtherewith and actuated through the link 432 by the pressure actuatedmechanism hereinbefore described in connection with Figure 20.

The load characteristic of this system is such that as the rotary valveis closed the torque of the impeller becomes reduced, and a relativelyhigh pressure air jet is formed at the control slot 52| to reenergizethe boundary layer.

With further reference to Figure 20, 525V is a compressed air storagevflask of spherical shape which is interconnected for charging, with thedischarge of the final stage 'air compressor through nipple 495, pipe521, check valves 520 and 529, and pipes 530 and 53| whereby air atfinal stage pressure of approximately 250 lbs. per square inch may bestored during operation of the power unit. An air compressor Aelectrically driven by a motor Mz serves to compress air from anatmospheric intake 532 to a pressure of approximately 300 lbs. persquare inch and deliver it through pipes 533 and 59| to the air flask525 for stand-by service or initial starting purposes.

The motor Mz is controlled by means of a pressure actuated switchingdevice 535 associated with the air storage flask 525 which functions toclose the motor circuit to operate the air compressor when the airpressure in said flask falls below a predetermined value. Y

A high speed compressed air operated turbine wheel 531 is mounted on thedrive shaft 538 of an electric generator E. The extension 539 of thegenerator shaft is coupled through an overrunning clutch 540 to theaccessory drive shaft |01 which extends radially from thecounterrotation differential transmission as described -hereinberforeprimarily in connection with Fig-

